Temperature boosting of waste heat from spacecraft by means of heat pumps makes it possible, under some conditions, to achieve considerable savings in radiator area and mass. This study considers several possibilities for employing workactuated and heat-actuated heat pumps (WAHP and HAHP, respectively) for this purpose. In the former case, the spacecraft power source is required to generate ext...

Problem-based Learning has been at the core of significant developments in engineering education in recent years. It refers to any learning environment in which the problem drives the learning. The problem is posed so that the students realize that they need to acquire some new knowledge before they can solve the problem. This paper presents an experience of a structured problem-based approach ...

Experiments were performed to measure the incipient boiling heat flux in a heat sink containing 21 rectangular (231 lm wide and 713 lm deep) micro-channels. Tests were performed using deionized water with inlet liquid velocities of 0.13–1.44 m/s, inlet temperatures of 30, 60 and 90 C, and an outlet pressure of 1.2 bar. Using a microscope, boiling incipience was identified when the first bubbles...

A novel, patented topping power cycle is described that takes its energy from a very high-temperature heat source and in which the temperature of the heat sink is still high enough to operate another, conventional power cycle. The top temperature heat source is used to evaporate a low saturation pressure liquid, which serves as the driving fluid for compressing the secondary fluid in an ejector...

heat-assisted magnetic recording Robert Fernandez, Desalegne Teweldebrhan, Chen Zhang, Alexander Balandin, and Sakhrat Khizroev Center for 3-D Electronics, Department of Electrical Engineering, University of California—Riverside, Riverside, California 92521, USA Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, University of California—R...

Low-grade heat from sources below 100 C o ers a vast quantity of energy. The ability to extract this energy, however, is limited with existing technologies as they are not well-suited to harvest energy from sources with variable heat output or with a small temperature di erence between the source and the environment. Here, we present a process for extracting energy from low-grade heat sources u...

Flow boiling heat transfer in parallel minichannels and microchannels is one of the solutions proposed for cooling high heat flux systems. The associated increase in the pressure drop poses a problem that needs to be studied in detail before the small diameter channels can be implemented in practical systems. The pressure drop fluctuations and the flow instability in a network of parallel chann...

An orientation of a grid is called unique sink orientation (USO) if each of its nonempty subgrids has a unique sink. Particularly, the original grid itself has a unique global sink. In this work we investigate the problem of how to find the global sink using minimum number of queries to an oracle. There are two different oracle models: the vertex query model where the orientation of all edges i...

k thermal conductivity, W/mK An analytical model is developed for predicting constriction and spreading resistances associated with heat transfer from various electronic components under different modes of cooling. The model assumes a heat source in contact with a larger cold plate which is in turn cooled with a convective heat transfer coefficient specified over the sink surface. Unlike existi...